1. Field of the Invention
The present invention relates generally to a relay, and more particularly to an electromagnetic relay having a structure for ensuring a sufficient insulating distance between certain parts of the relay.
2. Description of the Related Art
In a conventional electromagnetic relay including an electromagnet assembly and a contact section actuated by the electromagnet assembly to perform a make/break operation, it is known that the electromagnet assembly and the contact section are incorporated in a common base and that an insulating wall formed integrally with or separately from the base is interposed between the electromagnet assembly and the contact section so as to ensure a sufficient electrical insulation therebetween.
Japanese Unexamined Utility Model Publication (Kokai) No. 7-1554 (JP-U-7-1554) discloses an electromagnetic relay including an electromagnet assembly and a contact section, both incorporated in a common base. The electromagnet assembly has a structure wherein an armature, adapted to be driven by an electromagnet, is arranged oppositely to an axial end face of an iron core of the electromagnet in a pivotable manner, the end face extending generally orthogonal to a center axis of a coil. The contact section includes a movable contact member, adapted to be shifted due to the pivoting motion of the armature, and a pair of fixed contact members respectively disposed so as to oppositely face the both sides of the movable contact member, the movable and fixed contact members being arranged side-by-side along the coil center axis at a location away from the armature with the electromagnet placed between the contact members and the armature. The base is provided integrally with a first portion having a cylindrical wall for surrounding a part of the electromagnet assembly and a second portion having a plurality of receptive grooves for individually receiving the movable contact member and the fixed contact members in the contact section. In this structure, the cylindrical wall provided in the first portion of the base is interposed between the electromagnet assembly and the contact section so as to ensure an electrical insulation therebetween, and a separate insulator is additionally mounted adjacent to the cylindrical wall so as to enhance the insulation performance.
In this electromagnetic relay, each of the contact members in the contact section is provided with a contact portion at one longitudinal end, a terminal portion at another longitudinal end and a fitting portion between the contact and terminal ends, and the contact members are securely mounted to the second portion of the base by respectively fitting and inserting the fitting portions thereof in a lateral direction from one lateral edges of the fitting portions into the corresponding receptive grooves. In this regard, the fixed contact portions of the fixed contact members are respectively located at positions allowing the movable contact portion of the movable contact member disposed between the fixed contact members to alternately contact with the fixed contact portions in accordance with the pivoting motion of the armature. On the other hand, the terminal portions of the fixed and movable contact members project outward from the second portion of the base and are located in a line at predetermined intervals or pitches larger than the intervals of the contact portions. In this configuration, in order to ensure a predetermined insulating distance between the electromagnet assembly and the contact section as well as to maintain the predetermined terminal pitches in the contact section, the outside dimension of the electromagnetic relay tends to be increased relatively in a direction of the coil center axis, which results in a useless space around the contact portions of the contact members.
Japanese Unexamined Patent Publication (Kokai) No. 2000-268693 (JP-A-2000-268693) discloses an electromagnetic relay including an electromagnet assembly, and a contact section, which have a positional correlation similar to that of the electromagnet assembly and the contact section disclosed in JP-U-7-1554, but can effectively reduce the dimension along the coil center axis. In this electromagnetic relay, a base includes first and second portions formed as separate members and assembled together, the first portion being provided with a cylindrical wall for partially surrounding the electromagnet assembly, and the second portion being provided with a plurality of receptive grooves for individually receiving a movable contact member and a pair of fixed contact members in the contact section. When the first and second portions are properly assembled with each other, the cylindrical wall of the first portion is interposed between the electromagnet assembly and the contact section so as to ensure an electrical insulation therebetween.
Each of the contact members in the contact section is provided with a contact portion at one longitudinal end, a terminal portion at another longitudinal end and a fitting portion between the contact and terminal ends. The contact members are securely mounted to the second portion of the base by respectively fitting and inserting the fitting portions thereof in a longitudinal direction along the opposite lateral edges of the fitting portions into the corresponding receptive grooves. In this regard, one, or a break-side, fixed contact member, located close to the electromagnet assembly, is further provided between the fitting portion and the terminal portion with an extending portion extending generally orthogonal to both the fitting and terminal portions. When the break-side fixed contact member is properly fitted to the base, the extending portion is placed on the upper face of a plate-like part formed in the second portion and extending adjacent to the receptive grooves. Then, the first portion of the base is assembled to the second portion by laying the bottom face of the first portion on the extending portion of the break-side fixed contact member and placed on the plate-like part of the second portion. In this manner, the terminal portion of the break-side fixed contact member is located under the first portion of the base and the electromagnet assembly. As a result, it is possible to bring the contact portions of the contact members close to the electromagnet assembly, in comparison with the structure disclosed in JP-U-7-1554, while maintaining predetermined terminal pitches in the contact section, which results in the reduction of the outside dimension of the electromagnetic relay in the direction of the coil center axis.
However, in the above structure, in order to ensure a predetermined insulating distance between the electromagnet assembly and the contact section, it is required to keep the extending portion of the break-side fixed contact member away from the electromagnet assembly by a desired linear distance on the plate-like part of the second portion of the base, on which the extending portion is placed. As a result, the outside dimensions of the electromagnetic relay may be increased in the height direction thereof, otherwise, under the given limitation of the outside dimension, the dimension of the electromagnet in a radial direction of the coil and thus a space for installing a winding may be reduced, which may result in the degradation of a magnetic attraction force. Also, in comparison with the electromagnetic relay including the base having an integral or one-piece structure, the production cost may be increased due to the increased number of parts.
Incidentally, in the conventional electromagnetic relay having such a contact-member assembling structure that the contact members are mounted to the base by respectively fitting and inserting the fitting portions thereof in a longitudinal direction along the opposite lateral edges of the fitting portions into the corresponding receptive grooves formed in the base, the movable contact member having a relatively thinner shape for exhibiting a desired spring performance may especially be subjected to an undesirable deformation resulting in, e.g., a relative positional displacement between the contact and terminal portions, due to a pressing force applied to the movable contact member during the insertion thereof. Therefore, in this case, such a countermeasure has been generally adopted that the movable contact member is formed by fixedly joining two parts with each other, one being a thinner part including the contact portion and the other being a thicker part including the fitting and terminal portions, and that the pressing force during the insertion is loaded to the fitting portion in the thicker part (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 2000-149749 (JP-A-2000-149749) and U.S. Pat. No. 5,719,541).
However, in this structure, a production cost may be increased due to the increased number of parts, in comparison with the electromagnetic relay including the movable contact member having an integral or one-piece structure. Moreover, it is a general requirement in the conventional electromagnetic relay that the life of contact of each contact member in the contact section is effectively increased.
It is therefore an object of the present invention to provide an electromagnetic relay capable of ensuring a predetermined insulating distance between an electromagnet assembly and a contact section while maintaining predetermined terminal pitches in the contact section, and of improving a magnetic attraction force of the electromagnet without increasing the outside dimension of the relay, so as to ensure a high structural reliability and stable operating characteristics.
It is another object of the present invention to provide an electromagnetic relay, capable of avoiding the addition of parts, to prevent a production cost from increasing, without affecting a structural reliability and operating characteristics.
It is still another object of the present invention to provide an electromagnetic relay, capable of improving the life of respective contact members provided in a contact section.
In accordance with the present invention, there is provided an electromagnetic relay comprising a base including a receptacle; an electromagnet assembly incorporated in the base; and a contact section incorporated in the base to be actuated by the electromagnet assembly; the contact section including a fixed contact member located away from the electromagnet assembly at at least a predetermined insulating distance and a movable contact member located oppositely to the fixed contact member at a position further away from the electromagnet assembly than the fixed contact member; the fixed contact member being provided with a fixed contact portion, a first terminal portion, a fitting portion arranged between the fixed contact portion and the first terminal portion, the fitting portion being fitted and inserted in a lateral direction into the receptacle of the base, and an extending portion arranged between the fitting portion and the first terminal portion, the extending portion extending to be exposed outside from the receptacle; the movable contact member being provided with a movable contact portion capable of contacting with the fixed contact portion of the fixed contact member and a second terminal portion spaced from the first terminal portion of the fixed contact member; the extending portion of the fixed contact member being shaped and dimensioned to ensure at least the insulating distance and to maintain a predetermined terminal pitch between the first terminal portion of the fixed contact member and the second terminal portion of the movable contact member.
In this electromagnetic relay, it is preferred that the fitting portion of the fixed contact member extends in an angled shape in the receptacle of the base while keeping at least the insulating distance, and cooperates with the extending portion to maintain the terminal pitch.
It is also preferred that the insulating distance is 2 mm, or more, in a straight line.
It is advantageous that the extending portion of the fixed contact member is covered by an adhesive.
The electromagnet assembly may include an electromagnet with a coil; and the fixed contact member and the movable contact member may be arranged side-by-side in a row extending along a coil center axis of the electromagnet, and the extending portion of the fixed contact member extends in a direction generally parallel to the coil center axis.
In this arrangement, the electromagnet assembly may further include an armature driven by the electromagnet and a pair of coil terminal members connected respectively to opposite wire ends of the coil of the electromagnet, the pair of coil terminal members being arranged in a mutually spaced relationship in a direction generally orthogonal to the coil center axis; each of the coil terminal members may be provided with an entwining portion to which a wire end of the coil is securely entwined, a terminal portion projecting outward from the base and a bent portion arranged between the entwining portion and the terminal portion; and the pair of coil terminal members may define a larger space between entwining portions of the coil terminal members than a space between terminal portions of the coil terminal members, the armature being disposed in the larger space between the entwining portions.
Each of the coil terminal members may have a generally circular or regular-polygonal cross-sectional shape.
The electromagnet may include a bobbin for carrying the coil and the pair of coil terminal members, the bobbin being provided with a recess arranged adjacent to each of the coil terminal members for receiving a conductive wire of the coil.
It is also preferred that the base includes a second receptacle for receiving the movable contact member; and that the movable contact member is further provided with a fitting portion arranged between the movable contact portion and the second terminal portion to be fitted and inserted in a lateral direction into the second receptacle of the base, first and second loading portions dispersedly arranged around the movable contact portion to be subjected to a driving force applied from the electromagnet assembly, and a slit formed between the movable contact portion and the first loading portion to facilitate a shifting motion of the movable contact portion relative to the first loading portion.
In this arrangement, the movable contact portion may be spaced from the fitting portion in the movable contact member to define a generally U-shaped peripheral edge laterally opening to a side of the first loading portion.
The movable contact member may be further provided with an auxiliary slit formed between the movable contact portion and the second loading portion to facilitate a shifting motion of the movable contact portion relative to the second loading portion.
The auxiliary slit may be shaped asymmetrically to the slit about the movable contact portion.
The present invention also provides an electromagnetic relay comprising a base including a receptacle; an electromagnet assembly incorporated in the base; and a contact section incorporated in the base to be actuated by the electromagnet assembly; the contact section including a fixed contact member and a movable contact member; the fixed contact member being provided with a fixed contact portion and a first terminal portion; the movable contact member being provided with a movable contact portion capable of contacting with the fixed contact portion of the fixed contact member, a second terminal portion spaced from the first terminal portion of the fixed contact member, a fitting portion arranged between the movable contact portion and the second terminal portion to be fitted and inserted in a lateral direction into the receptacle of the base, first and second loading portions dispersedly arranged around the movable contact portion to be subjected to a driving force from the electromagnet assembly, and a slit formed between the movable contact portion and the first loading portion to facilitate a shifting motion of the movable contact portion relative to the first loading portion.
In this electromagnetic relay, it is preferred that the slit of the movable contact member defines an elastic arm including the first loading portion and disposed around the movable contact portion, the elastic arm being provided with a proximal end length extending adjacent to the generally U-shaped peripheral edge.
In this arrangement, the proximal end length of the elastic arm may extend in a curved manner adjacent to the generally U-shaped peripheral edge.